CDN over MongoDb GridFs with on the fly crop and resize for images

Features: on the fly crop and resize for image/png and image/jpeg mimetypes cache strategy, based on HTTP Last-Modified header additional metadata for each file & aggregated statistic for it forced HTTP Content-Disposition header with the file name, for download links(only if flag is specified, see below) buckets(MongoDB collections) as separation level file listings for buckets, queried by metadata or without